Copolymers of ethylene and unsaturated carboxylic acids, such as ethylene/acrylic acid, ethylene/methacrylic acid and the like, are known. It is known that such polymers can be produced as pellets, powders, small strands, and the like to increase the surface area/weight ratio. U.S. Pat. No. 3,798,194 discloses the digestion of ethylene/acrylic acid (EAA) polymers in an alcoholic alkali (e.g. NaOH) with stirring to spontaneously convert the polymer into colloidal size particles. U.S. Pat. No. 3,790,521 discloses the digestion of EAA polymers in an amine, with agitation, to produce non-colloidal size small particles and short, fine fibers. U.S. Pat. No. 3,801,551 discloses hot-drawing EAA polymers as strands, chopping the strands into pellets, digesting the pellets with an alkali, and shearing the pellets into short, fine fibers. Whereas such above forms of the polymers are operable in the invention described hereinafter, there has now been found a novel method of producing high surface area polymers (e.g. EAA) wherein the particles and fibers are large enough to be more easily managed than the colloidal sizes, and more efficient than the fine fibers of the above-discussed patents. In accordance with this novel polymer preparation, there are prepared particles and fibers which are highly porous, having a substantial amount of microporosity, thereby providing very high surface areas per bulk volume of the particles. This novel preparation is discussed more fully hereinafter.
As used in this disclosure, the term "melt index" (M.I.) refers to the melt flow rate value measured in accordance with ASTM D-1238.